Electric switch



May 5, 1925. 1,536,852

J. D. HILLIARD ELECTRIC SWITCH Filed Jan. 2, 1925:

Inventor: John D.Hillia-r'-oL His Attorneld;

i many times that produced Patented May 5, 1925 JOHN D. HILLIABID, F SOHENECTAIDY,

x YORK, ASSIGN OR TO GENERAL ELECTRIC 4 COMPANY, A CORPORATION or NEW YORIL nnncrnrc swrrcn.

Application filed January 2,

To all whom it may concem: Be- 1t known that I, JOHN D. HILLIARD,

a citizen of the United States, residing at Schenectady, county'of Schenectady, State of New York, have invented certain new and useful Improvements in Electric Switches,

of which the following is a specification.

an under highpressure, carbon tetrachloride, and other poly chloro derivatives. While all of the materials mentioned have characteristics which fit them to the "purpose of extinguishing an arc, theyalso pos sess certainunde'sirable features.

The interrupting capacity of awell 'designed fluid break switch is largely determmed by the pressure which its tank will withstand and this pressure, in turn, is dependent upon the volume of gas generated at the interruption of the circuit. trol and disposition of the gas generated at an ar between the contacts, comes a consid tance. The volume of this immersed. If the contacts are separated in a liquid of comparatively low resistance, the'I R heat of the liquid is added to the 4 arcand the interrupting capacity of the switch may be greatly reduced due to the fact that the volume of gas generated is by the are alone. ere large amounts of energy are to be interrupted. it is therefore important that 'an arc-extinguishing fluid of high resistance be used. v Where small amounts of power-at high voltage areto'be interrupted there is not the same necessity for a igh resistance fluid as where large amounts interrupted. Under these conditions it might appear desirable to use a fluid of comparatively low resistance because of the 1s invention relates to electric switches,

separation, the mostcommon of these materials being oil, water, d

v contacts and with I and PR heat of the b -a safe value.

of energy are to be of the oil and is 1923. Seria1No.610,099.

fact that the opening movement of the switch would be generated. With a single break in the circuit,'however, if the resistance of the liquid becomes so low as to conducta substantial amount of current the amountof gas generated with large currents will be destructive to the switch. On the other hand, if the resistance is high, for example substantially equal to that of distilled water, the amount of gas generated when opening low cureffective metal from the switch contacts and thereby Where inoperative.

rapidly separating the heavy currents the pressure due togas formation in both the water oil switch chambers materially accelcrates the separation of the switch members.

h1s action in oil switches is well knownto. be of importance in securing a quick break. It the resistance of the liquid in the And d tlons the water switch duty on the oil switch.

. uring normal condi-' switch is used in segreatly reduces the The use of oil as an arc extinguishing agent is advantageous in that it possesses excellent insulating characteristics, but under.

certain conditions is disadvantageous because it is vaporized and dissociated at the high temperature of and permanent gases nature and to set free a certain carbon which reduces the dielectric strength eventually deposited in the bottom of the switch tank as sludge.

the arc to form vapor of an inflammable is open to the The ejection of a mixture of oil, hot vapor ases from th tank by the pres and hot I sure pro need at an arc between the switch contacts "greatly increases the risk of fire and less serious objection that. it forms dirty spots on objects withwhich it (comes into contact.

These difiiculties may be largely avoided by the use of distilled water or a mixtureof water and glycerine where the switch is'to be used ata temperature below the freezing point of'water. Distilled water possesses excellent arc-extinguishing characteristics in that it does not form inflammable vapor and gases, is but slightly affected by repeated subjection 'to "the arc temperature, .and quickly evaporates if ejected from the tank.

' While water is vaporized and to some extent dissociated at the arc temperature, the gases into whichit is dissociated for, the

most part recombine to form water vapor which'is readily condensed. The high specific'heat ofwater and steam, the facility with which the dissociated gases recombine, and'the'readines with which the resulting .vapor is condensed to form water all contribute to make water a desirable arc-ex videdforv interrupting the circuit by a plu- .brea s being made in oil and some of them ralit of series connected breaks, some of the being made in water; This not only makes it feasible toutilize the greater interrupting capacity of water but also makes it possible I to tak e advantage of the'better insulating properties of oil. The interrupting cav tralize their undesirabl characteristics. By

pacity of a given switch may be further inereased by the provision of means for nitially internuptmg the circuit at the water lminersedcontacts, thereby reducing the heat generated in the oil. q

An ob'ectof my invention, therefore, is

to prom e means for employmg two or more arc-e tinguishing media in such a way as to utlllze theindeslrable qualities and new the use of a pluralitylof arc-extinguishing fluids, the interruptlng capacity of a given switch structure is greatly increased.

A. further object of my invention is to I provide meansby which the danger of fire and explosions caused by the operation of the switch isgreatly "reduced.

Other objects and advantages will be come apparent as my invention is described in detail. j

My invention-will be better understood from the following description taken-inconnection with the accompanying drawing,

and its scope will be pointed out in the appended claims.

Referring to ing, there is shown, partly in elevation and partly in section,.-a switch provided with terminals 1 electrically interconnected with auxiliary stationary contacts2 and tanks 3 upon the covers 4 of which are mounted the vmain stationary contacts 5. Bridging members 6 and 7 arranged to interconnect the single figure of the drawelectrically the main movable contacts 8 and n the auxiliary movable contact members 9 respectively, are mechanically associated with the operating rod 10 which may be made ofv insulating material and which is arranged to be moved by any suitable mech-.

anism. to operate the switch. Insulators 11 are supported through suitable openings in the covers 4 of the tanks 3 for the purpose of insulating the auxiliar contact rods 9 from the top and tank casmgs. [The switchas a whole is supported upon the member '12 and is insulatedtherefrom by the insulators 13, these insulators being suitably held to the support 12 by means of bolts 14..

Bafiles 15 are supported within the tanks 3 from the covers 4 by" rods 16, insulating "sleeves-17 being provided. for the purpose. of spacing these bafiies from each other,'to form a tortuous passage for any material ejected from the lower part of the tanks 3 by pressure producedat an are between the contacts to contain difl'erent arc extinguishmg uids water and oil, the water, tank being provided with a discharge pipe 19 which may contain a valve 20 and the oil tank being interconnected through an opening 21 I with a chamber 22 having perforated members 23 and 24 between which is placed a baflle composed ofgranular material such as gravel and the pur ose 'of which is to cool the hot gases and condense the vapor 2 and 9.. The tanks 3 are ada ted as is indicated on the drawing by the legends and oil ejected fromthe tank by pressure A created at an are between the switch contacts If the switch is to be used at a temperature below the freezing point, a mixture of water and glycerine-may be used in the water tank in lieu of water alone. f In operating the switch from the closed position" shown in the drawing, the-operat mg rod 10 is moved upwardly to separate the main contacts '5 and 8 which normally carry the most of the load current and which are connected between the switch terminals 1 in parallel with the auxiliary contacts 2 and 9 when the switch is in the illustrated closed position. By further upward movement, the auxiliary contacts 2 and 9 are separated to completely interrupt the circuit, the set of contacts in the water tank being shown as arranged to separate slightly in advance of those in the oil tank for the purpose of drawing most of the arc in the water or water mixture which is but slightly affected by repeated exposures to high temperatures. In closing the switch, the rod 10 is moved downwardly to close the circuit first at the auxiliary contacts 2and 9 and then at the primary contacts 5 and 8. y invention may be embodied in other forms than that 'shown and described and I, therefore, intend to cover by the appended claims all changes and modifications apparent to those skilled in the art and within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is, 1. An electric switch of the type wherein a circuit is broken by means of series-connected sets of contacts arranged upon the separation of the contacts in each set to extinguish any are which may be formed by drawing the same within an arc-extinguishing liquid, characterized by the fact that the respectivesets' of contacts are immersed in arc-extinguishing media of different characteristics whereby the desirable characteristics of said media are utilized and their undesirable characteristics are neutralized. 2. An electric switch comprising a plurality of series-connected sets of contacts,

separable and the other of which contains oil, a fixed contact secured in each tank beneath the surface of the liquld contalned there1n,.a pair of movable contacts arranged respectively to cooperate with said fixed contacts, and means for operating said movable contacts arranged first to separate the contacts which quently separate the contacts which are im mersedin oil, the separable pairs -of contacts being arranged to produce series breaks in the circuit controlled by the switch.

5. The method ofinterrupting a power circuit which consists in opening the circuit at a point under water whereby an arc is drawn, and during the drawing of said are opening the circuit at another point under oil.

In witness whereof I have hereunto set my hand this 29th day of December, 1922.

J OHN D. HILLIARD.

are immersed in water and subse- 

